EP0451266A1 - Method of manufacturing a plastic graded-index optical transmission element - Google Patents
Method of manufacturing a plastic graded-index optical transmission element Download PDFInfo
- Publication number
- EP0451266A1 EP0451266A1 EP89910922A EP89910922A EP0451266A1 EP 0451266 A1 EP0451266 A1 EP 0451266A1 EP 89910922 A EP89910922 A EP 89910922A EP 89910922 A EP89910922 A EP 89910922A EP 0451266 A1 EP0451266 A1 EP 0451266A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- optical transmission
- refractive index
- article
- index distribution
- transmission article
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/02033—Core or cladding made from organic material, e.g. polymeric material
- G02B6/02038—Core or cladding made from organic material, e.g. polymeric material with core or cladding having graded refractive index
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/04—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings formed by bundles of fibres
- G02B6/06—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings formed by bundles of fibres the relative position of the fibres being the same at both ends, e.g. for transporting images
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S359/00—Optical: systems and elements
- Y10S359/90—Methods
Definitions
- the present invention relates to an optical transmission article and a method of manufacturing same, which is useful for optical transmission lines such as near parabolic optical fibers, rod-like convergent lenses, and photosensors, as well as for an image transmitting array employed in a copying machine using a white light source.
- Optical transmission articles each with refractive indexes gradually distributed from the center toward the periphery on a cross-section thereof are disclosed in Japanese Examined Patent Publication No. 47-816, Japanese Examined Patent Publication No. 47-28059, and European Patent Publication No. 0208159.
- the distributed refractive index type optical transmission article disclosed in Japanese Examined Patent Publication No. 47-816 is made of glass and fabricated by an ion exchange method. This method, however, has a poor productivity and cannot produce articles having an identical shape (an identical length, in particular) and an identical performance. Even with an identical performance, the fabricated distributed refractive index type optical transmission articles have different lengths, and thus problems arise with the handling thereof.
- the distributed refractive index type optical transmission plastic article disclosed in Japanese Examined Patent Publication No. 47-28059 is made by mixing two or more transparent polymers having different refractive indexes and different solubilities with respect to a particular solvent.
- the mixed polymers are shaped into a rod or a fiber, and immersed in the solvent to extract a part of the polymers from the surface thereof, thereby changing a mixing ratio of the polymers from the surface toward the center thereof. Since the optical transmission article of this method is made of a mixture of two or more polymers having different refractive indexes, fluctuations in the refractive indexes of the article occur, deteriorating the transparency and causing light scattering, and therefore, the article cannot serve as the distributed refractive index type optical transmission article. Accordingly, little improvement can be expected in the application and development of this method.
- European Patent Publication No. 0208159 describes a method in which (A) at least one kind of thermoplastic polymer and (B) a monomer which is compatible with the polymer (A) when polymerized and forms a polymer having a refractive index different from that of the polymer (A), are mixed and formed into a rod-like shape. From the surface of the shaped body, the monomer (B) is volatilized to continuously distribute the monomer (B) from the surface toward the interior of the formed material, and thereafter, the non-polymerized monomer in the shaped body is polymerized to form a distributed refractive index type optical transmission plastic article.
- N N0(1 - ar2) This curve is considered to be the same as a curve " a " of Fig. 2.
- the distributed refractive index type optical transmission article fabricated according to the above-mentioned method provides a refractive index distribution curve " b " of Fig. 2.
- the curve b is relatively close to the ideal curve expressed by the equation (1).
- the refractive index distribution is greatly deviated from the ideal curve.
- the article When a grid pattern is observed through these optical transmission articles, if the optical transmission article has a refractive index pattern which almost correctly follows the quadratic curve defined by the equation (1), the article will provide a normal grid image as shown in Fig. 3(a). If, however, the refractive index distribution of the optical transmission article deviates from the ideal refractive index distribution, as indicated by (b) of Fig. 2, the article will provide a distorted grid image as shown in Figs. 3(b) and 3(c), since the article can not transmit a correct image. In this case, a moderation transfer factor (MTF) indicating the resolution of the article is very low, i.e., less than 30%, which is not acceptable for use as an optical transmission article of a copying machine.
- MTF moderation transfer factor
- the conventional distributed refractive index type optical transmission article with the refractive index distribution as shown by (b) of Fig. 2 must be cut or eluted by a solvent process to remove a portion outer than the position (d) of Fig. 2, thereby providing the optical transmission article with an optical path having a relatively ideal refractive index distribution. It is, however, difficult to provide an optical transmission article with a high resolution, and thus the productivity thereof is very low, and it is very difficult to constantly produce products having a uniform quality.
- An object of the invention is to provide a distributed refractive index type optical transmission plastic article which can be applied to a copying machine employing a white light source.
- the optical transmission article of the invention has a higher resolution, is brighter, and obtains a remarkably improved productivity.
- the invention also provides a method of manufacturing the distributed refractive index type optical transmission plastic article.
- This method employs N (N ⁇ 2) uncured liquid substances each having a viscosity of between 103 and 108 poises and refractive indexes n of n1 > n2 > n3 ... n N when cured, concentrically laminates the substances in such a way that the refractive indexes are successively reduced from the center toward the periphery of the laminated substances to form an uncured strand fiber, mutually diffuses the substances between adjacent layers in such a way that the refractive indexes are continuously distributed between the layers, and at the same time or thereafter, cures the uncured strand fiber.
- a refractive index distribution curve of the optical transmission article of the invention must substantially approximate the ideal refractive index distribution curve ((a) of Fig. 1) expressed with the equation (1), at least in a range of 0.25r0 to 0.70r0 , preferably 0.20r0 to 0.75r0 , from a center axis. If a distributed refractive index type optical transmission plastic article has a refractive index distribution curve which does not approximate the refractive index distribution curve (a) of Fig.
- the optical transmission article cannot correctly transfer images or satisfy the requirements for an optical transmission article applied to a copying machine, and therefore, can not be applied for such a purpose.
- the distributed refractive index type optical transmission plastic article of the invention must have a value n0 of 1.4 ⁇ n0 ⁇ 1.6. If the value exceeds 1.6, the optical transmission plastic article is difficult to produce, and if the value n0 is smaller than 1.4, a difference of refractive indexes at the center axis and at the periphery of the article cannot be enlarged, to thus realize an optical transmission article having an excellent resolution and image transmitting characteristics.
- the optical transmission article may have a chromatic aberration, and therefore, may not be appropriate for an optical transmission article used with a white light source.
- the optical transmission article may have a long image forming length and be difficult to handle.
- the distributed diffraction index type optical transmission plastic article of the invention When used for a copying machine, etc., a plurality of such articles, instead of a single article, are usually arranged in a single row or a plurality of rows in a zigzag manner, to form an array of the optical transmission materials in which images provided by the articles partly overlap each other to form an image.
- the visibility of the overlapped images depends on the degree of overlapping, which is influenced by the diameter of each optical transmission article. To obtain a clear image, the radius r0 must be in a range of 0.4 to 0.6 mm. If the article is thinner than this, the article may have an insufficient brightness and difficult to produce with a uniform refractive index distribution. If the article is thicker than the above range, the images provided by the array of the optical transmission articles may unevenly overlap each other, and thus will not transmit clear images.
- the MTF which indicates resolution of the distributed refractive index optical transmission plastic article of the invention, can be determined as follows. Namely, as shown in Fig. 4, a light source 42, a filter 43, a diffusion plate 44, a grid 45, and an array 47 composed of a plurality of distributed refractive index type optical transmission articles 41 form a resolution measuring apparatus. A grid image having a spatial frequency of 4 (line-pairs/mm) is passed through the optical transmission articles 41 to form an image on a CCD line sensor 46. The formed grid image is read, and a maximum value (i max ) and a minimum value (i min ) of light quantities of the image are measured as shown in Fig. 5.
- the MTF of the distributed refractive index type optical transmission plastic article of the invention must be not less than 55%. If the MTF is smaller than 55%, the optical transmission article provides a low resolution and cannot form a clear image when applied to a copying machine such as a facsimile.
- the distributed refractive index type optical transmission plastic article of the invention may be fabricated in the following manner: N (N ⁇ 2) uncured liquid substances each having a viscosity of between 103 and 108 poises in an uncured state and refractive indexes n of n1 > n2 > n3 ... n N in a cured state are prepared, and these uncured liquid substances are concentrically laminated, one upon the other, in such a way that the refractive indexes are successively reduced from the center toward the periphery of the laminated substances, thereby forming an uncured strand fiber.
- the substances of the strand fiber are then mutually diffused between adjacent layers to provide a continuous refractive index distribution between the layers, during which or thereafter the uncured strand fiber is cured.
- N ⁇ 2 is established in the distributed refractive index type optical transmission article having the value q of 0.3 > g ⁇ 0.15, a required difference n1 - n N may be set between a center layer and an outermost layer of the optical transmission material, and accordingly, it will become easy to fabricate the optical transmission article of the invention having a refractive index distribution which approximates the curve of the equation (1), in a range of 0.25r0 to 0.75r0 from the center of the article. Accordingly, N must be 2 or greater than 2, preferably 2 to 7, and more preferably 3 to 5.
- each of the uncured liquid substances must have a viscosity of between 103 and 108 poises and be curable. If the viscosity is smaller than 103 poises, the strand will be easily broken and it will be difficult to form a strand-like shape. If the viscosity is greater than 108 poises, the substance will have a poor shaping processability which will lead to a deterioration of the concentricity or the forming of irregular diameters.
- liquid substances to be employed when carrying out the invention may be radical polymerizable vinyl monomers, or compositions comprising the monomers and polymers that are soluble with the monomers.
- the uncured liquid substances are preferably composed of vinyl-based monomers and soluble polymers.
- the polymers able to be used must have a good compatibility with polymers produced from the radical polymerizable vinyl monomers.
- polymers having an identical refractive index for respective layers because an optical transmission plastic article having refractive indexes continuously distributed from the center toward the surface of the material can thus be formed.
- poly(methyl methacrylate) has an excellent transparency and a high refractive index, and therefore, is preferably used for producing the distributed refractive index type optical transmission article of the invention.
- thermosetting catalyst and/or photocatalyst to the uncured substances.
- the fiber strand containing the thermosetting catalyst and/or photocatalyst is heated or irradiated with light, preferably ultraviolet light.
- the thermosetting catalyst may be a peroxide-based catalyst
- the photopolymerization catalyst may be benzophenone, benzoinalkylether, 4'-isopropyl-2-hydroxy-2-methyl-propiophenone, 1-hydroxycyclohexylphenylketone, benzylmethylketal, 2,2-diethoxyacetophenone, chlorothioxanthone, thioxanthone-based compounds, benzophenone-based compounds, 4-dimethylaminobenzoic ethyl, 4-dimethylaminobenzoic isoamyl, N-methyldiethanolamine, triethylamine, etc.
- the light source used for the photopolymerization may be a carbon arc lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a low-pressure mercury lamp, a chemical lamp, a xenon lamp, or a laser beam, etc., emitting light having a wavelength of 150 to 600 nm.
- a strand fiber forming apparatus shown in Fig. 6, for example may be used.
- a concentric composite nozzle 61 extrudes an uncured strand fiber 62, which is passed through a mutual diffusion portion 63 for mutually diffusing monomers of respective layers of the strand fiber to impart a refractive index distribution, as well as through a curing portion 64 for curing the uncured substances.
- the strand fiber is then passed between pulling rollers 65, and wound, as a distributed refractive index type optical transmission plastic article 66, around a winding portion 67.
- an inert gas such as a nitrogen gas is introduced from an inert gas introducing port 68, and discharged from a discharging port 69.
- the distributed refractive index type optical transmission article obtained according to the above method may have a coating layer with a low refractive index.
- the coating layer can be formed by mixing trifluoroalkylacrylate, pentafluoroalkylacrylate, hexafluoroalkylacrylate, fluoroalkylenediacrylate, 1,1,2, 2-tetrahydroheptadecafluorodecylacrylate, hexanedioldiacrylate, neopentylglycoldiacrylate, dipentaerythritolhexaacrylate, etc.
- polymers of fluorized acrylate or methacrylate may be added to adjust the applicability and refractive indexes.
- the lens capacities and refractive index distributions of the examples were measured as follows:
- the lens capacities were measured with an evaluation apparatus shown in Fig. 7.
- Each optical transmission article prepared according to the Examples was cut to a length of about one fourth ( ⁇ /4) of a period ( ⁇ ) of a light beam.
- the period ( ⁇ ) was determined from the wave form of a He-Ne laser beam passing through the article.
- the article was then polished with a polisher, to make both end faces of the sample parallel to each other and orthogonal to a longitudinal axis, and thus a sample to be evaluated was obtained.
- a sample table (76) was placed on an optical bench (71), and a sample (78) to be evaluated was placed on the sample table (76).
- a diaphragm (74) was adjusted so that light from a light source (72) passes through a condenser lens (73), the diaphragm (74), and a glass plate (75) and entirely irradiates an end face of the sample.
- the sample (78) and a Polaroid camera (77) were adjusted so that the light was focused on a film in a Polaroid (a trademark of the Polaroid company) camera. An image of a square grid was photographed, and a distortion of the grid was observed.
- the glass plate (75) was a chrome-plated photomasking glass, the chrome film on which was precisely processed to form a square grid pattern of 0.1 mm.
- MEK methylethylketone
- the three kinds of the original liquids were simultaneously extruded from a composite nozzle to form a concentric strand fiber. During this extrusion, the viscosity of the first layer components was 4.7 x 104 poises, that of the second layer components was 3.7 x 104 poises, and that of the third layer components was 2.9 x 104 poises.
- the temperature of the composite nozzle was 60°C.
- the strand fiber 62 extruded from the nozzle was passed through the mutual diffusion portion (63) 45 cm in length, to mutually diffuse the monomers between layers of the strand fiber.
- the strand fiber was passed through the center of a light irradiating portion composed of 12 fluorescent lamps (120 cm long, output 40 W) equidistantly arranged in a ring shape, at a speed of 40 cm/min, and as a result, the monomers in the strand fiber were polymerized to form a distributed refractive index type optical transmission plastic article which was then drawn by nip rollers.
- the distributed refractive index type optical transmission article thus produced had a radius (r0) of 0.59 mm, distributed refractive indexes measured by the Interfaco interference microscope of 0.508 at a central portion and 1.498 at a peripheral portion, and a refractive index distribution constant (g) of 0.20 mm ⁇ 1.
- a refractive index distribution of the article substantially approximated the equation (1), in a range of 0.15r0 to 0.75r0 extending from the center toward the external face of the article.
- Both end surfaces of the optical transmission article were polished to a lens length of 18.4 mm, and an MTF thereof was measured with a grid of 4 line-pairs/mm; the MTF was 60% at a conjugate length of 42.4 mm.
- the obtained grid image was clear with only a minor distortion.
- a plurality of the optical transmission articles were employed to form an optical transmission article array having a lens length of 18.4 mm as indicated by the numeral 47 in Fig. 4, an MTF thereof was measured with a grid of 4 line-pairs/mm, and it was found that the MTF was 52%. At this time, a conjugate length of a rod-like lens forming the optical transmission article array was 42.4 mm.
- This optical transmission article array, an LED light source, and a light receiving CCD element were assembled into an image scanner, which provided a high resolution and was able to transmit clear images.
- the three kinds of original liquids used in the Example 1 and a fourth layer forming original liquid made of poly(methyl methacrylate) ([ ⁇ ] 0.34 measured in MEK at 25°C) of 47 parts by weight, methylmethacrylate of 40 parts by weight, 2,2,3,3,4,4,5,5-octafluoropentylmethacrylate of 13 parts by weight, 1-hydroxycyclohexylphenylketone of 0.2 parts by weight, and hydroquinone of 0.1 part by weight were heated and mixed at 60°C to form uncured substances, and thereafter, the four kinds of original liquids were simultaneously extruded from a concentric four-layer composite spinning nozzle to form a concentric strand fiber.
- the viscosities of the first, second, and third layers were substantially the same as those of the Example 1, and the viscosity of the fourth layer-forming components was 2.5 x 104 poises.
- the temperature of the composite nozzle was 60°C.
- Example 2 Thereafter, the same processes as in Example 1 were carried out to provide a distributed refractive index type optical transmission plastic article.
- the optical transmission article thus produced had a radius (r0) of 0.60 mm, distributed refractive indexes measured by the Interfaco interference microscope of 1.507 at a central portion and 1.496 at a peripheral portion, and a refractive index distribution constant (g) of 0.20 mm ⁇ 1.
- a refractive index distribution of the article substantially approximated the equation (1), in a range of 0.15r0 to 0.80r0 extending from the center toward the external face of the article.
- Both end surfaces of the optical transmission article were polished to a lens length of 18.4 mm, the MTF thereof was measured with a grid of 4 line-pairs/mm, and it was found that the MTF was 65% at a conjugate length of 42.4 mm.
- a plurality of the optical transmission articles were employed to form an optical transmission article array having a lens length of 18.4 mm, in a manner similar to the Example 1.
- This optical transmission article array, an LED light source, and a light receiving CCD element were assembled into an image scanner, which provided a high resolution and was able to transmit clear images.
- the four kinds of original liquids used in the Example 2 were used as original liquids for forming first to fourth layers.
- the viscosities of the first, second, third, and fourth layers were substantially the same as those of Example 2, and the viscosity of the fifth layer-forming components was 2.2 x 104 poises.
- the temperature of the composite nozzle was 60°C.
- Example 2 Thereafter, the same processes as in Example 1 were carried out to provide a distributed refractive index type optical transmission plastic article.
- a ratio of discharged quantities of the first, second, third, fourth, and fifth layers was 7:4:1.1:0.6:0.4.
- the optical transmission article thus produced had a radius (r0) of 0.60 mm, distributed refractive indexes measured by the Interfaco interference microscope of 1.507 at a central portion and 1.494 at a peripheral portion, and a refractive index distribution constant (g) of 0.20 mm ⁇ 1.
- a refractive index distribution of the article substantially approximated the equation (1), in a range of 0.15r0 to 0.85r0 extending from the center toward the external surface of the article.
- Both end surfaces of the optical transmission article were polished to a lens length of 17.8 mm, the MTF thereof was measured with a grid of 4 line-pairs/mm, and it was found that the MTF was 72% at a conjugate length of 32.6 mm.
- a plurality of the optical transmission articles were formed into an optical transmission article array having a lens length of 17.8 mm, in a manner similar to Example 1.
- An MTF of the array measured with the grid of 4 line-pairs/mm was 65% at a conjugate length of 32.6 mm.
- This optical transmission article array, an LED light source, and a light receiving CCD element were assembled into an image scanner, which provided a high resolution and was able to transmit clear images.
- Example 2 The same four kinds of original liquids as those used in the Example 2 were employed at a ratio of discharged quantities of the first, second, third, and fourth layers of 1:1:1:1. The other conditions were the same as those of Example 2 in forming a strand fiber.
- the monomers were diffused, and the curing process was carried out to prepare an optical transmission article having a radius (r0) of 0.55 mm, distributed refractive indexes measured by the Interfaco interference microscope of 1.506 at a central portion and 1.486 at a peripheral portion, and a refractive index distribution constant (g) of 0.29 mm ⁇ 1.
- the refractive index distribution of the article agreed with the equation (1) for only about 10% of the radial range.
- Both end surfaces of the optical transmission article were polished to a lens length of 13.5 mm, and the MTF of the article measured with a grid of 4 line-pairs/mm, was 22% at a conjugate length of 24.7 mm.
- a plurality of the optical transmission articles were assembled into an optical transmission article array having a lens length of 13.5 mm in a similar manner to Example 1.
- An MTF of the array measured with the grid of 4 line-pairs/mm was 19% at a conjugate length of 24.7 mm.
- This optical transmission article array, an LED light source, and a light receiving CCD element were assembled into an image scanner, which provided a very poor resolution.
- the original liquid for forming the third layer used in the Example 1 was used as an original liquid for forming a second layer.
- the original liquid for forming the fourth layer used in the Example 2 was used as an original liquid for forming a third layer.
- These three kinds of original liquids were used to prepare a distributed refractive index type optical transmission material in a manner similar to the Example 1. At this time, the viscosity of the first layer-forming components was 4.5 x 104 poises.
- the prepared optical transmission article had a radius (r0) of 0.46 mm, distributed refractive indexes measured by the Interfaco interference microscope of 1.500 at a central portion and 1.490 at a peripheral portion, and a refractive index distribution constant (g) of 0.25 mm ⁇ 1.
- a refractive index distribution of the article substantially approximated the equation (1) in a range of 0.15r0 to 0.81r0 extending from the center toward the external face of the article.
- Both end surfaces of the optical transmission article were polished to a lens length of 15.6 mm, the MTF thereof was measured with a grid of 4 line-pairs/mm, and it was found that the MTF was 62% at a conjugate length of 29.0 mm.
- a plurality of the optical transmission articles were employed to form an optical transmission article array having a lens length of 15.6 mm in a manner similar to Example 1.
- An MTF of the array measured with the grid of 4 line-pairs/mm was 55% at a conjugate length of 29.0 mm.
- This optical transmission article array, an LED light source, and a light receiving CCD element were assembled into an image scanner, which provided a high resolution and was able to transmit clear images.
- the polymer [A] of 46 parts by weight, 2,2,3,3-tetrafluoropropylmethacrylate of 44 parts by weight, methylmethacrylate of 10 parts by weight, 1-hydroxycyclohexylphenylketone of 0.2 part by weight, and hydroquinone of 0.1 part by weight were heated and mixed at 60°C to form an uncured substance as an original liquid for forming a third layer.
- the three kinds of original liquids were spun to form a composite in a manner similar to Example 1 at the viscosities of 4.0 x 104 poises for the first layer-forming components, 3.3 x 104 poises for the second layer-forming components, and 3.1 x 104 poises for the third layer-forming components.
- the prepared optical transmission article had a radius (r0) of 0.50 mm, distributed refractive indexes measured by the Interfaco interference microscope of 1.472 at a central portion and 1.459 at a peripheral portion, and a refractive index distribution constant (g) of 0.27 mm ⁇ 1.
- a refractive index distribution of the article substantially approximated the equation (1), in a range of 0.15r0 to 0.78r0 extending from the center toward the external face of the article.
- Both end surfaces of the optical transmission article were polished to a lens length of 14.0 mm, the MTF thereof was measured with a grid of 4 line-pairs/mm, and it was found that the MTF was 64% at a conjugate length of 29.0 mm.
- a plurality of the optical transmission articles were employed to form an optical transmission article array having a lens length of 14.0 mm in a manner similar to Example 1.
- An MTF of the array measured with the grid of 4 line-pairs/mm was 57% at a conjugate length of 29 mm.
- This optical transmission article array, an LED light source, and a light receiving CCD element were assembled into an image scanner, which provided a high resolution and was able to transmit clear images.
- the distributed refractive index type optical transmission plastic article of the invention substantially approximates the ideal distribution curve of the equation (1), at least in a range of 0.25r0 to 0.75r0 from the center of the article, and therefore, without a cutting of the peripheral portion thereof, the article of the invention provides excellent lens characteristics.
- the distribution refractive index type optical transmission article of the invention therefore, can be applied to an image transmitting array of a copying machine employing a white light source, and to an optical transmission line such as a near parabolic optical fiber, a rod-like convergent lens, and an optical sensor.
- the optical transmission article of the invention can be efficiently manufactured by a multilayer extrusion method of concentrically extruding two or more layers from uncured substances.
Abstract
Description
- The present invention relates to an optical transmission article and a method of manufacturing same, which is useful for optical transmission lines such as near parabolic optical fibers, rod-like convergent lenses, and photosensors, as well as for an image transmitting array employed in a copying machine using a white light source.
- Optical transmission articles each with refractive indexes gradually distributed from the center toward the periphery on a cross-section thereof are disclosed in Japanese Examined Patent Publication No. 47-816, Japanese Examined Patent Publication No. 47-28059, and European Patent Publication No. 0208159.
- The distributed refractive index type optical transmission article disclosed in Japanese Examined Patent Publication No. 47-816 is made of glass and fabricated by an ion exchange method. This method, however, has a poor productivity and cannot produce articles having an identical shape (an identical length, in particular) and an identical performance. Even with an identical performance, the fabricated distributed refractive index type optical transmission articles have different lengths, and thus problems arise with the handling thereof.
- The distributed refractive index type optical transmission plastic article disclosed in Japanese Examined Patent Publication No. 47-28059 is made by mixing two or more transparent polymers having different refractive indexes and different solubilities with respect to a particular solvent. The mixed polymers are shaped into a rod or a fiber, and immersed in the solvent to extract a part of the polymers from the surface thereof, thereby changing a mixing ratio of the polymers from the surface toward the center thereof. Since the optical transmission article of this method is made of a mixture of two or more polymers having different refractive indexes, fluctuations in the refractive indexes of the article occur, deteriorating the transparency and causing light scattering, and therefore, the article cannot serve as the distributed refractive index type optical transmission article. Accordingly, little improvement can be expected in the application and development of this method.
- European Patent Publication No. 0208159 describes a method in which (A) at least one kind of thermoplastic polymer and (B) a monomer which is compatible with the polymer (A) when polymerized and forms a polymer having a refractive index different from that of the polymer (A), are mixed and formed into a rod-like shape. From the surface of the shaped body, the monomer (B) is volatilized to continuously distribute the monomer (B) from the surface toward the interior of the formed material, and thereafter, the non-polymerized monomer in the shaped body is polymerized to form a distributed refractive index type optical transmission plastic article.
-
- According to studies and measurements made by the inventor, using an Interfaco interference microscope under conditions to be explained later, however, the distributed refractive index type optical transmission article fabricated according to the above-mentioned method provides a refractive index distribution curve "b" of Fig. 2. In a range of 0.5r₀ to 0.75r₀ of radial distances from the center (i.e., in a range of c to d in the figure, with e being an outermost part), the curve b is relatively close to the ideal curve expressed by the equation (1). At the outer and inner sides of the above range, however, the refractive index distribution is greatly deviated from the ideal curve.
- When a grid pattern is observed through these optical transmission articles, if the optical transmission article has a refractive index pattern which almost correctly follows the quadratic curve defined by the equation (1), the article will provide a normal grid image as shown in Fig. 3(a). If, however, the refractive index distribution of the optical transmission article deviates from the ideal refractive index distribution, as indicated by (b) of Fig. 2, the article will provide a distorted grid image as shown in Figs. 3(b) and 3(c), since the article can not transmit a correct image. In this case, a moderation transfer factor (MTF) indicating the resolution of the article is very low, i.e., less than 30%, which is not acceptable for use as an optical transmission article of a copying machine.
- Accordingly, the conventional distributed refractive index type optical transmission article with the refractive index distribution as shown by (b) of Fig. 2 must be cut or eluted by a solvent process to remove a portion outer than the position (d) of Fig. 2, thereby providing the optical transmission article with an optical path having a relatively ideal refractive index distribution. It is, however, difficult to provide an optical transmission article with a high resolution, and thus the productivity thereof is very low, and it is very difficult to constantly produce products having a uniform quality.
- An object of the invention is to provide a distributed refractive index type optical transmission plastic article which can be applied to a copying machine employing a white light source. Compared with the conventional optical transmission articles, the optical transmission article of the invention has a higher resolution, is brighter, and obtains a remarkably improved productivity.
- The invention provides a distributed refractive index type optical transmission plastic article having a circular cross section of a radius r₀ and a refractive index distribution which substantially approximates a refractive index distribution curve defined by the following equation (1), at least in a range of 0.25r₀ to 0.70r₀ extending from a center axis toward a peripheral surface of the optical transmission article:
where n₀ is a refractive index at the center axis of the optical transmission article;
n(r) is a refractive index at a position of a radius r away from the center axis of the optical transmission article;
q is a refractive index distribution constant (mm⁻¹) of the optical transmission article; and
r is a distance (mm) from the center axis toward the peripheral surface of the optical transmission article, wherein,
1.4 ≦ n₀ ≦ 1.6
0.4 ≦ r₀ (mm) ≦ 0.6
0.15 ≦ g (mm⁻¹) < 0.3
said distributed refractive index type optical transmission plastic article having a modulation transfer function (hereinafter referred to as the MTF) of not less than 55%, calculated according to the following equation (2):
when a grid image of 4 line-pairs/mm is formed through the optical transmission article on a CCD line sensor and a maximum value imax and a minimum value imin of light quantities of the image are measured. - The invention also provides a method of manufacturing the distributed refractive index type optical transmission plastic article. This method employs N (N ≧ 2) uncured liquid substances each having a viscosity of between 10³ and 10⁸ poises and refractive indexes n of n₁ > n₂ > n₃ ... nN when cured, concentrically laminates the substances in such a way that the refractive indexes are successively reduced from the center toward the periphery of the laminated substances to form an uncured strand fiber, mutually diffuses the substances between adjacent layers in such a way that the refractive indexes are continuously distributed between the layers, and at the same time or thereafter, cures the uncured strand fiber.
-
- Fig. 1 shows a refractive index distribution curve of an example of distributed refractive index type optical transmission articles of the invention;
- Fig. 2 shows a refractive index distribution curve of a distributed refractive index type optical transmission plastic article formed according to a prior art method;
- Fig. 3 is a view of examples of grid images obtained by these optical transmission articles;
- Fig. 4 is a schematic view of an apparatus for measuring the resolution of an optical transmission article;
- Fig. 5 is a graph showing the light quantity levels of a grid image measured with a CCD sensor;
- Fig. 6 is a schematic view of an apparatus preferably used for forming the distributed refractive index type optical transmission plastic article of the invention;
- Fig. 7 is a schematic view of a lens capacity measuring apparatus; and
- Fig. 8 shows a refractive index distribution curve of an example of distributed refractive index type optical transmission plastic optical articles of the invention.
- As indicated by (b) of Fig. 1, a refractive index distribution curve of the optical transmission article of the invention must substantially approximate the ideal refractive index distribution curve ((a) of Fig. 1) expressed with the equation (1), at least in a range of 0.25r₀ to 0.70r₀ , preferably 0.20r₀ to 0.75r₀ , from a center axis. If a distributed refractive index type optical transmission plastic article has a refractive index distribution curve which does not approximate the refractive index distribution curve (a) of Fig. 1 expressed with the equation (1), in a range of 0.25r₀ to 0.70r₀ from a center axis, the optical transmission article cannot correctly transfer images or satisfy the requirements for an optical transmission article applied to a copying machine, and therefore, can not be applied for such a purpose.
- The distributed refractive index type optical transmission plastic article of the invention must have a value n₀ of 1.4 ≦ n₀ ≦ 1.6. If the value exceeds 1.6, the optical transmission plastic article is difficult to produce, and if the value n₀ is smaller than 1.4, a difference of refractive indexes at the center axis and at the periphery of the article cannot be enlarged, to thus realize an optical transmission article having an excellent resolution and image transmitting characteristics.
- A value q is defined by the following equation (3):
which defines a lens length and an image forming length. When the value g is greater than 0.3 mm⁻¹, the optical transmission article may have a chromatic aberration, and therefore, may not be appropriate for an optical transmission article used with a white light source. When the value q is smaller than 0.15 mm⁻¹, the optical transmission article may have a long image forming length and be difficult to handle. - When the distributed diffraction index type optical transmission plastic article of the invention is used for a copying machine, etc., a plurality of such articles, instead of a single article, are usually arranged in a single row or a plurality of rows in a zigzag manner, to form an array of the optical transmission materials in which images provided by the articles partly overlap each other to form an image. The visibility of the overlapped images depends on the degree of overlapping, which is influenced by the diameter of each optical transmission article. To obtain a clear image, the radius r₀ must be in a range of 0.4 to 0.6 mm. If the article is thinner than this, the article may have an insufficient brightness and difficult to produce with a uniform refractive index distribution. If the article is thicker than the above range, the images provided by the array of the optical transmission articles may unevenly overlap each other, and thus will not transmit clear images.
- The MTF, which indicates resolution of the distributed refractive index optical transmission plastic article of the invention, can be determined as follows. Namely, as shown in Fig. 4, a
light source 42, afilter 43, adiffusion plate 44, agrid 45, and anarray 47 composed of a plurality of distributed refractive index typeoptical transmission articles 41 form a resolution measuring apparatus. A grid image having a spatial frequency of 4 (line-pairs/mm) is passed through theoptical transmission articles 41 to form an image on aCCD line sensor 46. The formed grid image is read, and a maximum value (imax) and a minimum value (imin) of light quantities of the image are measured as shown in Fig. 5. According to the measured imax and imin , the MTF is calculated from the following equation (2):
where the grid constant is the number of lines per millimeter (line-pairs/mm), in which each line comprises a pair of white and black lines as shown on thegrid 45 of Fig. 4. - The MTF of the distributed refractive index type optical transmission plastic article of the invention must be not less than 55%. If the MTF is smaller than 55%, the optical transmission article provides a low resolution and cannot form a clear image when applied to a copying machine such as a facsimile.
- The distributed refractive index type optical transmission plastic article of the invention may be fabricated in the following manner:
N (N ≧ 2) uncured liquid substances each having a viscosity of between 10³ and 10⁸ poises in an uncured state and refractive indexes n of n₁ > n₂ > n₃ ... nN in a cured state are prepared, and these uncured liquid substances are concentrically laminated, one upon the other, in such a way that the refractive indexes are successively reduced from the center toward the periphery of the laminated substances, thereby forming an uncured strand fiber. The substances of the strand fiber are then mutually diffused between adjacent layers to provide a continuous refractive index distribution between the layers, during which or thereafter the uncured strand fiber is cured. - If N ≧ 2 is established in the distributed refractive index type optical transmission article having the value q of 0.3 > g ≧ 0.15, a required difference n₁ - nN may be set between a center layer and an outermost layer of the optical transmission material, and accordingly, it will become easy to fabricate the optical transmission article of the invention having a refractive index distribution which approximates the curve of the equation (1), in a range of 0.25r₀ to 0.75r₀ from the center of the article. Accordingly, N must be 2 or greater than 2, preferably 2 to 7, and more preferably 3 to 5.
- When carrying out the invention, each of the uncured liquid substances must have a viscosity of between 10³ and 10⁸ poises and be curable. If the viscosity is smaller than 10³ poises, the strand will be easily broken and it will be difficult to form a strand-like shape. If the viscosity is greater than 10⁸ poises, the substance will have a poor shaping processability which will lead to a deterioration of the concentricity or the forming of irregular diameters.
- The liquid substances to be employed when carrying out the invention may be radical polymerizable vinyl monomers, or compositions comprising the monomers and polymers that are soluble with the monomers.
- The radical polymerizable vinyl monomers are, for example, methyl methacrylate (n = 1.49), styrene (n = 1.59), chlorostyrene (n = 1.61), vinyl acetate (n = 1.47), fluorized alkyl(meta)acrylate (n = 1.37 to 1.44) such as 2,2,3,3-tetrafluoropropyl(meta)acrylate, 2,2,3,3,4,4,5,5-octafluoropropyl(meta)acrylate, 2,2,3,4,4,4-hexafluoropropyl(meta)acrylate, and 2,2,2-trifluoroethyl(meta)acrylate, and (meta)acrylates having a refractive index between 1.43 and 1.62 such as ethyl(meta)acrylate, phenyl(meta)acrylate, benzyl(meta)acrylate, hydroxylalkyl(meta)acrylate, alkyleneglycoldi(meta)acrylate, trimethylolpropane-di or -tri(meta)acrylate, pentaerythritol-di, -tri, or -tetra(meta)acrylate, diglycerintetra(meta)acrylate, dipentaerythritolhexa(meta)acrylate, as well as diethyleneglycolbisallylcarbonate, fluorized alkyleneglycolpoly(meta)acrylate, etc.
- In order to adjust the viscosities of these cured liquid substances and make the distribution of the refractive index of an obtained strand fiber from the center toward the outside of the strand fiber, the uncured liquid substances are preferably composed of vinyl-based monomers and soluble polymers. The polymers able to be used must have a good compatibility with polymers produced from the radical polymerizable vinyl monomers. These polymers are, for example, poly(methyl methacrylate) (n = 1.49), poly(methyl methacrylate)-based copolymers (n = 1.47 to 1.50), poly-4-methylpenten-1 (n = 1.46), ethylene/vinyl acetate copolymers (n = 1.46 to 1.50), polycarbonate (n = 1.50 to 1.57), poly(vinylidene fluoride) (n = 1.42), vinylidene fluoride/tetrafluoroethylene copolymers (n = 1.42 to 1.46), vinylidene fluoride/tetrafluoroethylene/hexafluoropropene copolymers (n = 1.40 to 1.46), and poly(alkyl fluoride)(meta)acrylate polymers.
- To adjust the viscosities, it is preferable to use polymers having an identical refractive index for respective layers, because an optical transmission plastic article having refractive indexes continuously distributed from the center toward the surface of the material can thus be formed. In particular, poly(methyl methacrylate) has an excellent transparency and a high refractive index, and therefore, is preferably used for producing the distributed refractive index type optical transmission article of the invention.
- To cure the strand fiber formed from the uncured substances, it is preferable to add a thermosetting catalyst and/or photocatalyst to the uncured substances. The fiber strand containing the thermosetting catalyst and/or photocatalyst is heated or irradiated with light, preferably ultraviolet light.
- The thermosetting catalyst may be a peroxide-based catalyst, and the photopolymerization catalyst may be benzophenone, benzoinalkylether, 4'-isopropyl-2-hydroxy-2-methyl-propiophenone, 1-hydroxycyclohexylphenylketone, benzylmethylketal, 2,2-diethoxyacetophenone, chlorothioxanthone, thioxanthone-based compounds, benzophenone-based compounds, 4-dimethylaminobenzoic ethyl, 4-dimethylaminobenzoic isoamyl, N-methyldiethanolamine, triethylamine, etc.
- The light source used for the photopolymerization may be a carbon arc lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a low-pressure mercury lamp, a chemical lamp, a xenon lamp, or a laser beam, etc., emitting light having a wavelength of 150 to 600 nm.
- To produce the optical transmission article of the invention, a strand fiber forming apparatus shown in Fig. 6, for example, may be used. A concentric composite nozzle 61 extrudes an
uncured strand fiber 62, which is passed through amutual diffusion portion 63 for mutually diffusing monomers of respective layers of the strand fiber to impart a refractive index distribution, as well as through a curingportion 64 for curing the uncured substances. The strand fiber is then passed between pullingrollers 65, and wound, as a distributed refractive index type opticaltransmission plastic article 66, around a windingportion 67. To remove volatilizing substances released from thestrand fiber 62, from themutual diffusion portion 63 and from the curingportion 64, an inert gas such as a nitrogen gas is introduced from an inertgas introducing port 68, and discharged from a dischargingport 69. - The distributed refractive index type optical transmission article obtained according to the above method may have a coating layer with a low refractive index. The coating layer can be formed by mixing trifluoroalkylacrylate, pentafluoroalkylacrylate, hexafluoroalkylacrylate, fluoroalkylenediacrylate, 1,1,2, 2-tetrahydroheptadecafluorodecylacrylate, hexanedioldiacrylate, neopentylglycoldiacrylate, dipentaerythritolhexaacrylate, etc. As and when required, polymers of fluorized acrylate or methacrylate may be added to adjust the applicability and refractive indexes. In addition, it is preferable to add photopolymerization initiators.
- The invention will be explained in more detail with reference to Examples.
- The lens capacities and refractive index distributions of the examples were measured as follows:
- The lens capacities were measured with an evaluation apparatus shown in Fig. 7.
- Each optical transmission article prepared according to the Examples was cut to a length of about one fourth (λ/4) of a period (λ) of a light beam. The period (λ) was determined from the wave form of a He-Ne laser beam passing through the article. The article was then polished with a polisher, to make both end faces of the sample parallel to each other and orthogonal to a longitudinal axis, and thus a sample to be evaluated was obtained.
- As shown in Fig. 7, a sample table (76) was placed on an optical bench (71), and a sample (78) to be evaluated was placed on the sample table (76). A diaphragm (74) was adjusted so that light from a light source (72) passes through a condenser lens (73), the diaphragm (74), and a glass plate (75) and entirely irradiates an end face of the sample. Thereafter, the sample (78) and a Polaroid camera (77) were adjusted so that the light was focused on a film in a Polaroid (a trademark of the Polaroid company) camera. An image of a square grid was photographed, and a distortion of the grid was observed. The glass plate (75) was a chrome-plated photomasking glass, the chrome film on which was precisely processed to form a square grid pattern of 0.1 mm.
- An Interfaco interference microscope made by the Carl Zeiss company was used for this measurement.
- Poly(methyl methacrylate) ([η] = 0.34 measured in methylethylketone (MEK) at 25°C) of 52 parts by weight, benzylmethacrylate of 35 parts by weight, methylmethacrylate of 13 parts by weight, 1-hydroxycyclohexylphenylketone of 0.2 parts by weight, and hydroquinone of 0.1 parts by weight were heated and mixed at 60°C to form an uncured substance as an original liquid for forming a first layer (a central portion). Poly(methyl methacrylate) ([η] = 0.34 measured in MEK at 25°C) of 50 parts by weight, benzylmethacrylate of 15 parts by weight, methylmethacrylate of 35 parts by weight, 1-hydroxycyclohexylphenylketone of 0.2 parts by weight, and hydroquinone of 0.1 parts by weight were heated and mixed at 60°C to form an uncured substance as an original liquid for forming a second layer. Poly(methyl methacrylate) ([η] = 0.34 measured in MEK at 25°C) of 50 parts by weight, methylmethacrylate of 50 parts by weight, 1-hydroxycyclohexylphenylketone of 0.2 parts by weight, and hydroquinone of 0.1 parts by weight were heated and mixed to form an uncured substance as an original liquid for forming a third layer (outer layer portion). The three kinds of the original liquids were simultaneously extruded from a composite nozzle to form a concentric strand fiber. During this extrusion, the viscosity of the first layer components was 4.7 x 10⁴ poises, that of the second layer components was 3.7 x 10⁴ poises, and that of the third layer components was 2.9 x 10⁴ poises. The temperature of the composite nozzle was 60°C. As shown in Fig. 6, the
strand fiber 62 extruded from the nozzle was passed through the mutual diffusion portion (63) 45 cm in length, to mutually diffuse the monomers between layers of the strand fiber. Thereafter, the strand fiber was passed through the center of a light irradiating portion composed of 12 fluorescent lamps (120 cm long, output 40 W) equidistantly arranged in a ring shape, at a speed of 40 cm/min, and as a result, the monomers in the strand fiber were polymerized to form a distributed refractive index type optical transmission plastic article which was then drawn by nip rollers. - When forming the strand fiber, a ratio f discharged quantities of the first, second, and third layers was 7:4:1. The distributed refractive index type optical transmission article thus produced had a radius (r₀) of 0.59 mm, distributed refractive indexes measured by the Interfaco interference microscope of 0.508 at a central portion and 1.498 at a peripheral portion, and a refractive index distribution constant (g) of 0.20 mm⁻¹. As shown in Fig. 8, a refractive index distribution of the article substantially approximated the equation (1), in a range of 0.15r₀ to 0.75r₀ extending from the center toward the external face of the article. Both end surfaces of the optical transmission article were polished to a lens length of 18.4 mm, and an MTF thereof was measured with a grid of 4 line-pairs/mm; the MTF was 60% at a conjugate length of 42.4 mm. The obtained grid image was clear with only a minor distortion.
- A plurality of the optical transmission articles were employed to form an optical transmission article array having a lens length of 18.4 mm as indicated by the numeral 47 in Fig. 4, an MTF thereof was measured with a grid of 4 line-pairs/mm, and it was found that the MTF was 52%. At this time, a conjugate length of a rod-like lens forming the optical transmission article array was 42.4 mm. This optical transmission article array, an LED light source, and a light receiving CCD element were assembled into an image scanner, which provided a high resolution and was able to transmit clear images.
- The three kinds of original liquids used in the Example 1 and a fourth layer forming original liquid made of poly(methyl methacrylate) ([η] = 0.34 measured in MEK at 25°C) of 47 parts by weight, methylmethacrylate of 40 parts by weight, 2,2,3,3,4,4,5,5-octafluoropentylmethacrylate of 13 parts by weight, 1-hydroxycyclohexylphenylketone of 0.2 parts by weight, and hydroquinone of 0.1 part by weight were heated and mixed at 60°C to form uncured substances, and thereafter, the four kinds of original liquids were simultaneously extruded from a concentric four-layer composite spinning nozzle to form a concentric strand fiber. During this extrusion, the viscosities of the first, second, and third layers were substantially the same as those of the Example 1, and the viscosity of the fourth layer-forming components was 2.5 x 10⁴ poises. The temperature of the composite nozzle was 60°C.
- Thereafter, the same processes as in Example 1 were carried out to provide a distributed refractive index type optical transmission plastic article.
- When forming the strand fiber, a ratio of discharged quantities of the first, second, third, and fourth layers was 7:4:1:0.5. The optical transmission article thus produced had a radius (r₀) of 0.60 mm, distributed refractive indexes measured by the Interfaco interference microscope of 1.507 at a central portion and 1.496 at a peripheral portion, and a refractive index distribution constant (g) of 0.20 mm⁻¹. A refractive index distribution of the article substantially approximated the equation (1), in a range of 0.15r₀ to 0.80r₀ extending from the center toward the external face of the article. Both end surfaces of the optical transmission article were polished to a lens length of 18.4 mm, the MTF thereof was measured with a grid of 4 line-pairs/mm, and it was found that the MTF was 65% at a conjugate length of 42.4 mm. A plurality of the optical transmission articles were employed to form an optical transmission article array having a lens length of 18.4 mm, in a manner similar to the Example 1. An MTF of the array, measured with a grid of 4 line-pairs/mm, was 58% at a conjugate length of 42.4 mm. This optical transmission article array, an LED light source, and a light receiving CCD element were assembled into an image scanner, which provided a high resolution and was able to transmit clear images.
- The four kinds of original liquids used in the Example 2 were used as original liquids for forming first to fourth layers. Poly(methyl methacrylate) ([η] = 0.34 measured in MEK at 25°C) of 40 parts by weight, methylmethacrylate of 18 parts by weight, 2,2,3,3,4,4,6,6-octafluoropentylmethacrylate of 42 parts by weight, 1-hydroxycyclohexylphenylketone of 0.2 parts by weight, and hydroquinone of 0.1 part by weight were heated and mixed at 60°C to form a fifth layer, and thereafter, the five kinds of original liquids were simultaneously extruded from a composite nozzle to form a concentric strand fiber. During this extrusion, the viscosities of the first, second, third, and fourth layers were substantially the same as those of Example 2, and the viscosity of the fifth layer-forming components was 2.2 x 10⁴ poises. The temperature of the composite nozzle was 60°C.
- Thereafter, the same processes as in Example 1 were carried out to provide a distributed refractive index type optical transmission plastic article. When forming the strand fiber, a ratio of discharged quantities of the first, second, third, fourth, and fifth layers was 7:4:1.1:0.6:0.4. The optical transmission article thus produced had a radius (r₀) of 0.60 mm, distributed refractive indexes measured by the Interfaco interference microscope of 1.507 at a central portion and 1.494 at a peripheral portion, and a refractive index distribution constant (g) of 0.20 mm⁻¹. A refractive index distribution of the article substantially approximated the equation (1), in a range of 0.15r₀ to 0.85r₀ extending from the center toward the external surface of the article. Both end surfaces of the optical transmission article were polished to a lens length of 17.8 mm, the MTF thereof was measured with a grid of 4 line-pairs/mm, and it was found that the MTF was 72% at a conjugate length of 32.6 mm. A plurality of the optical transmission articles were formed into an optical transmission article array having a lens length of 17.8 mm, in a manner similar to Example 1. An MTF of the array measured with the grid of 4 line-pairs/mm was 65% at a conjugate length of 32.6 mm. This optical transmission article array, an LED light source, and a light receiving CCD element were assembled into an image scanner, which provided a high resolution and was able to transmit clear images.
- The same four kinds of original liquids as those used in the Example 2 were employed at a ratio of discharged quantities of the first, second, third, and fourth layers of 1:1:1:1. The other conditions were the same as those of Example 2 in forming a strand fiber. The monomers were diffused, and the curing process was carried out to prepare an optical transmission article having a radius (r₀) of 0.55 mm, distributed refractive indexes measured by the Interfaco interference microscope of 1.506 at a central portion and 1.486 at a peripheral portion, and a refractive index distribution constant (g) of 0.29 mm⁻¹. The refractive index distribution of the article agreed with the equation (1) for only about 10% of the radial range. Both end surfaces of the optical transmission article were polished to a lens length of 13.5 mm, and the MTF of the article measured with a grid of 4 line-pairs/mm, was 22% at a conjugate length of 24.7 mm. A plurality of the optical transmission articles were assembled into an optical transmission article array having a lens length of 13.5 mm in a similar manner to Example 1. An MTF of the array measured with the grid of 4 line-pairs/mm was 19% at a conjugate length of 24.7 mm. This optical transmission article array, an LED light source, and a light receiving CCD element were assembled into an image scanner, which provided a very poor resolution.
- Poly(methyl methacrylate) ([η] = 0.34 measured in MEK at 25°C) of 51 parts by weight, benzylmethacrylate of 20 parts by weight, methylmethacrylate of 29 parts by weight, 1-hydroxycyclohexylphenylketone of 0.2 parts by weight, and hydroquinone of 0.1 part by weight were heated and mixed at 60°C to form an uncured substance as an original liquid for forming a first layer. The original liquid for forming the third layer used in the Example 1 was used as an original liquid for forming a second layer. The original liquid for forming the fourth layer used in the Example 2 was used as an original liquid for forming a third layer. These three kinds of original liquids were used to prepare a distributed refractive index type optical transmission material in a manner similar to the Example 1. At this time, the viscosity of the first layer-forming components was 4.5 x 10⁴ poises.
- When forming a strand fiber, a ratio of discharged quantities of the first, second, and third layers was 7:3:1. The prepared optical transmission article had a radius (r₀) of 0.46 mm, distributed refractive indexes measured by the Interfaco interference microscope of 1.500 at a central portion and 1.490 at a peripheral portion, and a refractive index distribution constant (g) of 0.25 mm⁻¹. A refractive index distribution of the article substantially approximated the equation (1) in a range of 0.15r₀ to 0.81r₀ extending from the center toward the external face of the article. Both end surfaces of the optical transmission article were polished to a lens length of 15.6 mm, the MTF thereof was measured with a grid of 4 line-pairs/mm, and it was found that the MTF was 62% at a conjugate length of 29.0 mm. A plurality of the optical transmission articles were employed to form an optical transmission article array having a lens length of 15.6 mm in a manner similar to Example 1. An MTF of the array measured with the grid of 4 line-pairs/mm was 55% at a conjugate length of 29.0 mm. This optical transmission article array, an LED light source, and a light receiving CCD element were assembled into an image scanner, which provided a high resolution and was able to transmit clear images.
- A polymer [A] (n₀ = 1.456, [η] = 1.00 measured in MEK at 25°C) of 50 parts by weight composed of methylmethacrylate of 50% by weight and 2,2,3,3-tetrafluoropropylmethacrylate of 50% by weight, methylmethacrylate of 50 parts by weight, 1-hydroxycyclohexylphenylketone of 0.2 part by weight, and hydroquinone of 0.1 part by weight were heated and mixed at 60°C to form an uncured substance as an original liquid for forming a first layer. The above polymer [A] of 48 parts by weight, 2,2,3,3-tetrafluoropropylmethacrylate of 22 parts by weight, methylmethacrylate of 30 parts by weight, 1-hydroxycyclohexylphenylketone of 0.2 part by weight, and hydroquinone of 0.1 part by weight were heated and mixed at 60°C to form an uncured substance as an original liquid for forming a second layer. The polymer [A] of 46 parts by weight, 2,2,3,3-tetrafluoropropylmethacrylate of 44 parts by weight, methylmethacrylate of 10 parts by weight, 1-hydroxycyclohexylphenylketone of 0.2 part by weight, and hydroquinone of 0.1 part by weight were heated and mixed at 60°C to form an uncured substance as an original liquid for forming a third layer. The three kinds of original liquids were spun to form a composite in a manner similar to Example 1 at the viscosities of 4.0 x 10⁴ poises for the first layer-forming components, 3.3 x 10⁴ poises for the second layer-forming components, and 3.1 x 10⁴ poises for the third layer-forming components.
- When forming the strand fiber, a ratio of discharged quantities of the first, second, and third layers was 7:4:1. The prepared optical transmission article had a radius (r₀) of 0.50 mm, distributed refractive indexes measured by the Interfaco interference microscope of 1.472 at a central portion and 1.459 at a peripheral portion, and a refractive index distribution constant (g) of 0.27 mm⁻¹. A refractive index distribution of the article substantially approximated the equation (1), in a range of 0.15r₀ to 0.78r₀ extending from the center toward the external face of the article. Both end surfaces of the optical transmission article were polished to a lens length of 14.0 mm, the MTF thereof was measured with a grid of 4 line-pairs/mm, and it was found that the MTF was 64% at a conjugate length of 29.0 mm. A plurality of the optical transmission articles were employed to form an optical transmission article array having a lens length of 14.0 mm in a manner similar to Example 1. An MTF of the array measured with the grid of 4 line-pairs/mm was 57% at a conjugate length of 29 mm. This optical transmission article array, an LED light source, and a light receiving CCD element were assembled into an image scanner, which provided a high resolution and was able to transmit clear images.
- Compared with an optical transmission article of a prior art of the same kind, the distributed refractive index type optical transmission plastic article of the invention substantially approximates the ideal distribution curve of the equation (1), at least in a range of 0.25r₀ to 0.75r₀ from the center of the article, and therefore, without a cutting of the peripheral portion thereof, the article of the invention provides excellent lens characteristics. The distribution refractive index type optical transmission article of the invention, therefore, can be applied to an image transmitting array of a copying machine employing a white light source, and to an optical transmission line such as a near parabolic optical fiber, a rod-like convergent lens, and an optical sensor.
- The optical transmission article of the invention can be efficiently manufactured by a multilayer extrusion method of concentrically extruding two or more layers from uncured substances.
-
- 41:
- optical transmission article
- 42:
- light source
- 43:
- filter
- 44:
- diffusion plate
- 45:
- grid
- 46:
- CCD line sensor
- 47:
- array
- 61:
- composite nozzle
- 62:
- uncured strand fiber
- 63:
- mutual diffusion portion
- 64:
- curing portion
- 65:
- take-up roller
- 66:
- optical transmission article
- 67:
- winding portion
- 71:
- optical bench
- 72:
- light source
- 73:
- condenser lens
- 74:
- diaphragm
- 75:
- glass plate
- 76:
- sample table
- 77:
- Polaroid camera
- 78:
- sample
Claims (4)
- A distributed refractive index type optical transmission plastic article having a circular cross section of a radius r₀ and a refractive index distribution which substantially approximates a refractive index distribution curve defined by the following equation (1) at least in a range of 0.25r₀ to 0.70r₀ extending from a center axis toward a peripheral surface of the optical transmission article:
where n₀ is a refractive index at the center axis of the optical transmission article;
n(r) is a refractive index at a position of radius r away from the center axis of the optical transmission article;
g is a refractive index distribution constant (mm⁻¹) of the optical transmission article;
r is a distance (mm) from the center axis toward the peripheral surface of the optical transmission article; and
1.4 ≦ n₀ ≦ 0.6
0.4 ≦ r₀ (mm) ≦ 0.6
0.15 ≦ g (mm⁻¹) < 0.3
wherein when a grid image of 4 line-pairs/mm is formed through the optical transmission article on a CCD line sensor and a maximum value imax and a minimum value imin of light quantities of the image are measured, a modulation transfer function (MTF) calculated according to the following equation (2):
is at least 55%. - A distributed refractive index type optical transmission plastic article as set forth in claim 1, wherein the refractive index distribution of the optical transmission article substantially approximates the refractive index distribution curve defined by the equation (1) at least in a range of 0.20r₀ to 0.75r₀ extending from the center axis toward the peripheral surface of the optical transmission article.
- A method of manufacturing a distributed refractive index type optical transmission plastic article comprising the steps of preparing N (N ≧ 2) uncured liquid substances having a viscosity between 10³ and 10⁸ poises each and refractive indexes n of n₁ > n₂ > n₃ ... nN when cured, concentrically laminating the substances in such a way that the refractive indexes are successively reduced from the center toward the periphery of the laminated substances to form an uncured strand fiber, mutually diffusing the substances between adjacent layers in such a way that the refractive indexes are continuously distributed between the layers, and at the same time or thereafter, curing the uncured strand fiber.
- An optical transmission article array comprising an assembly of a plurality of distributed refractive index type plastic optical transmission articles arranged in a single line or a plurality of lines, said distributed refractive index type optical transmission plastic articles each having a circular cross section of a radius r₀ and a refractive index distribution which substantially approximates a refractive index distribution curve defined by the following equation (1) at least in a range of 0.25r₀ to 0.70r₀ extending from a center axis toward a peripheral surface of the optical transmission article:
where n₀ is a refractive index at the center axis of the optical transmission article;
n(r) is a refractive index at a position of radius r away from the center axis of the optical transmission article;
g is a refractive index distribution constant (mm⁻¹) of the optical transmission article;
r is a distance (mm) from the center axis toward the peripheral face of the optical transmission article; and
1.4 ≦ n₀ ≦ 1.6
0.4 ≦ r₀ (mm) ≦ 0.6
0.15 ≦ g (mm⁻¹) < 0.3
wherein when a grid image of 4 line-pairs/mm is formed through the optical transmission article on a CCD line sensor and a maximum value imax and a minimum value imin of light quantities of the image are measured, a modulation transfer function (MTF) calculated according to the following equation (2):
is at least 55%.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/JP1989/000991 WO1991005275A1 (en) | 1989-09-29 | 1989-09-29 | Refractive index distribution type plastic optical transfer member and its production method |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0451266A1 true EP0451266A1 (en) | 1991-10-16 |
EP0451266A4 EP0451266A4 (en) | 1992-07-08 |
EP0451266B1 EP0451266B1 (en) | 1995-12-13 |
Family
ID=13958872
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP89910922A Expired - Lifetime EP0451266B1 (en) | 1989-09-29 | 1989-09-29 | Method of manufacturing a plastic graded-index optical transmission element |
Country Status (5)
Country | Link |
---|---|
US (1) | US5390274A (en) |
EP (1) | EP0451266B1 (en) |
KR (1) | KR0151706B1 (en) |
DE (1) | DE68925125T2 (en) |
WO (1) | WO1991005275A1 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1997020240A1 (en) * | 1995-11-30 | 1997-06-05 | Akzo Nobel N.V. | Method of making graded index polymeric optical fibres |
US5729645A (en) * | 1996-08-13 | 1998-03-17 | The Trustees Of The University Of Pennsylvania | Graded index optical fibers |
EP0866348A2 (en) * | 1997-03-17 | 1998-09-23 | Sumitomo Wiring Systems, Ltd. | Method for manufacturing a graded refractive index plastic optical-fiber and apparatus therefor |
US6106745A (en) * | 1995-11-30 | 2000-08-22 | Akzo Nobel Nv | Method of making graded index polymeric optical fibers |
US9731456B2 (en) | 2013-03-14 | 2017-08-15 | Sabic Global Technologies B.V. | Method of manufacturing a functionally graded article |
Families Citing this family (23)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5557701A (en) * | 1993-12-02 | 1996-09-17 | Ceramoptec Industries, Inc. | Power laser delivery fiber system with enhanced damage threshold |
US5861129A (en) * | 1995-09-13 | 1999-01-19 | Katoot; Mohammad W. | Polymer optical fibers and process for manufacture thereof |
US6200503B1 (en) | 1996-09-13 | 2001-03-13 | Mohammad W. Katoot | Graded index polymer optical fibers and process for manufacture thereof |
US6091872A (en) * | 1996-10-29 | 2000-07-18 | Katoot; Mohammad W. | Optical fiber imaging system |
JP3728032B2 (en) * | 1996-10-31 | 2005-12-21 | 三菱レイヨン株式会社 | Low chromatic aberration rod lens array and unit thereof, and image scanner using them |
US5935491A (en) * | 1997-09-15 | 1999-08-10 | University Of Massachusettes | Gradient-index polymer rods and fibers |
US6088166A (en) * | 1998-12-22 | 2000-07-11 | Dicon Fiberoptics, Inc. | Miniaturization of gradient index lens used in optical components |
US6365072B1 (en) | 1999-03-19 | 2002-04-02 | Mk Industries, Inc. | Polymer optical fibers and process for manufacturing thereof |
US20030132536A1 (en) * | 2001-12-31 | 2003-07-17 | General Components, Inc. | Method of making a graded index polymer optical fiber |
EP1472073A1 (en) * | 2001-12-31 | 2004-11-03 | General Components Inc. | Optical fiber production system and crosshead die therefor |
DE10214533B4 (en) * | 2002-04-02 | 2004-11-25 | Deutsche Telekom Ag | Method and device for producing an optical polymer fiber |
US20050157999A1 (en) * | 2002-12-27 | 2005-07-21 | Zhen Zhen | Graded index polymer optical fiber and a method of making the same |
WO2005103774A1 (en) * | 2004-04-22 | 2005-11-03 | Lite-On Japan Ltd. | Production method for graded index type optical transmission element |
US9703011B2 (en) | 2013-05-07 | 2017-07-11 | Corning Incorporated | Scratch-resistant articles with a gradient layer |
US9110230B2 (en) | 2013-05-07 | 2015-08-18 | Corning Incorporated | Scratch-resistant articles with retained optical properties |
US9359261B2 (en) | 2013-05-07 | 2016-06-07 | Corning Incorporated | Low-color scratch-resistant articles with a multilayer optical film |
US9684097B2 (en) | 2013-05-07 | 2017-06-20 | Corning Incorporated | Scratch-resistant articles with retained optical properties |
US9366784B2 (en) | 2013-05-07 | 2016-06-14 | Corning Incorporated | Low-color scratch-resistant articles with a multilayer optical film |
US11267973B2 (en) | 2014-05-12 | 2022-03-08 | Corning Incorporated | Durable anti-reflective articles |
US9335444B2 (en) | 2014-05-12 | 2016-05-10 | Corning Incorporated | Durable and scratch-resistant anti-reflective articles |
US9790593B2 (en) | 2014-08-01 | 2017-10-17 | Corning Incorporated | Scratch-resistant materials and articles including the same |
KR102591067B1 (en) | 2015-09-14 | 2023-10-18 | 코닝 인코포레이티드 | Anti-reflective product with high light transmittance and scratch resistance |
CN114085038A (en) | 2018-08-17 | 2022-02-25 | 康宁股份有限公司 | Inorganic oxide articles with thin durable antireflective structures |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4568146A (en) * | 1982-10-21 | 1986-02-04 | Sumitomo Electric Industries, Ltd. | Plastic optical fiber and production thereof |
EP0208159A2 (en) * | 1985-06-12 | 1987-01-14 | Mitsubishi Rayon Co., Ltd. | Process for Producing an optical Transmission Medium |
EP0242636A2 (en) * | 1986-03-27 | 1987-10-28 | Mitsubishi Rayon Co., Ltd. | Plastic optical transmission medium, process for producing the same and array of lenses using the same |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4331380A (en) * | 1980-05-21 | 1982-05-25 | Xerox Corporation | Gradient index lens array having reduction properties |
US4435039A (en) * | 1981-11-02 | 1984-03-06 | Xerox Corporation | Method and apparatus for improving image quality of a reduction/enlargement gradient index lens array |
US4589736A (en) * | 1984-11-23 | 1986-05-20 | Xerox Corporation | Two row reduction/enlargement gradient index lens array having square-ended fibers |
JPS62215204A (en) * | 1986-03-17 | 1987-09-21 | Mitsubishi Rayon Co Ltd | Production of plastic optical transmission body |
KR0154877B1 (en) * | 1989-09-29 | 1998-12-15 | 나가이 야타로 | Refractive index distribution type plastic optical transfer member and its production method |
-
1989
- 1989-09-29 US US07/908,603 patent/US5390274A/en not_active Expired - Lifetime
- 1989-09-29 KR KR1019910700529A patent/KR0151706B1/en not_active IP Right Cessation
- 1989-09-29 WO PCT/JP1989/000991 patent/WO1991005275A1/en active IP Right Grant
- 1989-09-29 EP EP89910922A patent/EP0451266B1/en not_active Expired - Lifetime
- 1989-09-29 DE DE68925125T patent/DE68925125T2/en not_active Expired - Lifetime
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4568146A (en) * | 1982-10-21 | 1986-02-04 | Sumitomo Electric Industries, Ltd. | Plastic optical fiber and production thereof |
EP0208159A2 (en) * | 1985-06-12 | 1987-01-14 | Mitsubishi Rayon Co., Ltd. | Process for Producing an optical Transmission Medium |
EP0242636A2 (en) * | 1986-03-27 | 1987-10-28 | Mitsubishi Rayon Co., Ltd. | Plastic optical transmission medium, process for producing the same and array of lenses using the same |
Non-Patent Citations (2)
Title |
---|
APPLIED OPTICS. vol. 21, no. 15, August 1982, NEW YORK US pages 2739 - 2746; W. LAMA: 'Optical properties of GRIN fiber lens arrays: dependence on fiber length' * |
See also references of WO9105275A1 * |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1997020240A1 (en) * | 1995-11-30 | 1997-06-05 | Akzo Nobel N.V. | Method of making graded index polymeric optical fibres |
US6106745A (en) * | 1995-11-30 | 2000-08-22 | Akzo Nobel Nv | Method of making graded index polymeric optical fibers |
US5729645A (en) * | 1996-08-13 | 1998-03-17 | The Trustees Of The University Of Pennsylvania | Graded index optical fibers |
US5911025A (en) * | 1996-08-13 | 1999-06-08 | The Trustees Of The University Of Pennsylvania | Method for the preparation of optical fibers |
EP0866348A2 (en) * | 1997-03-17 | 1998-09-23 | Sumitomo Wiring Systems, Ltd. | Method for manufacturing a graded refractive index plastic optical-fiber and apparatus therefor |
EP0866348A3 (en) * | 1997-03-17 | 1998-12-02 | Sumitomo Wiring Systems, Ltd. | Method for manufacturing a graded refractive index plastic optical-fiber and apparatus therefor |
US9731456B2 (en) | 2013-03-14 | 2017-08-15 | Sabic Global Technologies B.V. | Method of manufacturing a functionally graded article |
Also Published As
Publication number | Publication date |
---|---|
EP0451266A4 (en) | 1992-07-08 |
KR0151706B1 (en) | 1998-12-15 |
US5390274A (en) | 1995-02-14 |
DE68925125T2 (en) | 1996-05-30 |
KR920702888A (en) | 1992-10-28 |
DE68925125D1 (en) | 1996-01-25 |
EP0451266B1 (en) | 1995-12-13 |
WO1991005275A1 (en) | 1991-04-18 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP0451266B1 (en) | Method of manufacturing a plastic graded-index optical transmission element | |
US4822122A (en) | Optical transmission medium and process for producing the same based on vinylidene flouride polymers and metharylate polymers | |
EP0447548B1 (en) | Method of manufacturing a plastic graded-index optical transmission element | |
US4799761A (en) | Plastic optical transmission medium, process for producing the same and array of lenses using the same | |
EP1909118A1 (en) | Plastic rod lens, rod lens array, rod lens plate, image sensor, and printer | |
EP0527239B1 (en) | Manufacturing method of a graded index type optical transmission element | |
JP3072116B2 (en) | Manufacturing method of graded index plastic optical transmitter | |
JP3291583B2 (en) | Indexable plastic optical transmitter, optical transmitter array, and image scanner | |
JP3328615B2 (en) | Graded-index plastic optical transmitter | |
US7058270B2 (en) | Method for preparing plastic optical fiber preform | |
JPH03192310A (en) | Manufacture of plastic optical transmission body | |
JP3370658B2 (en) | Graded-index plastic optical transmitter | |
JPH063533A (en) | Production of distributed refractive index type plastic light transmission body | |
JP2893046B2 (en) | Method of manufacturing refractive index distribution type plastic optical transmission body | |
JPH11352307A (en) | Method for using light transmission body or light transmission body array, and color image sensor | |
JP3008361B2 (en) | Manufacturing method of graded index plastic optical transmitter | |
JPS62108208A (en) | Plastic optical transmission body and its production | |
JP3945849B2 (en) | OPTICAL TRANSMITTER, OPTICAL TRANSMITTER ARRAY, USE THEREOF, AND COLOR IMAGE SENSOR | |
JPH04251805A (en) | Refractive index distribution type plastic optical transmission body | |
JPH0735929A (en) | Gradient index optical transmission body | |
JPH07146416A (en) | Refraction factor distribution type light transmission body, and manufacture thereof | |
JP2010139959A (en) | Plastic rod lens, method of manufacturing the same, and plastic rod lens array | |
JPH10221540A (en) | Light transmitter, its manufacture, and its array | |
JPH0553017A (en) | Linear light emitting body | |
JPH0225804A (en) | Production of plastic light transmission body |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
17P | Request for examination filed |
Effective date: 19910528 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): CH DE FR GB LI NL |
|
A4 | Supplementary search report drawn up and despatched |
Effective date: 19920515 |
|
AK | Designated contracting states |
Kind code of ref document: A4 Designated state(s): CH DE FR GB LI NL |
|
17Q | First examination report despatched |
Effective date: 19940610 |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): CH DE FR GB LI NL |
|
REF | Corresponds to: |
Ref document number: 68925125 Country of ref document: DE Date of ref document: 19960125 |
|
REG | Reference to a national code |
Ref country code: CH Ref legal event code: NV Representative=s name: BUGNION S.A. |
|
ET | Fr: translation filed | ||
PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
26N | No opposition filed | ||
REG | Reference to a national code |
Ref country code: GB Ref legal event code: IF02 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: CH Payment date: 20050928 Year of fee payment: 17 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: CH Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20060930 Ref country code: LI Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20060930 |
|
REG | Reference to a national code |
Ref country code: CH Ref legal event code: PL |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FR Payment date: 20080915 Year of fee payment: 20 Ref country code: NL Payment date: 20080915 Year of fee payment: 20 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: DE Payment date: 20081002 Year of fee payment: 20 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: GB Payment date: 20081001 Year of fee payment: 20 |
|
REG | Reference to a national code |
Ref country code: GB Ref legal event code: PE20 Expiry date: 20090928 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: NL Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION Effective date: 20090929 Ref country code: GB Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION Effective date: 20090928 |
|
NLV7 | Nl: ceased due to reaching the maximum lifetime of a patent |